People with severe mental illness (SMI), and particularly those dually diagnosed with comorbid substance use disorder (SUD), are at extremely elevated risk for several serious blood-borne infections, including HIV, Hepatitis B and Hepatitis C. One third of dually diagnosed clients in many mental health service settings are likely to have one of these infections, and the rate of co-infection is very high. However, the field lacks effective and feasible models for responding to this problem, and neither infected nor high-risk clients receive services that meet authoritative standards. Indeed, infected clients may be the least likely of all people with SMI to receive adequate medical care. By and large, mental health providers are not well informed regarding these issues, and do not systematically provide the necessary interventions to help clients understand and cope with these risks and diseases. Providers do, however, express interest and willingness to respond by increasing staff education and by adding services for their high-risk clients. To date, no such innovation has been reported in any state mental health system, even in those states with known high rates of seroprevalence. Barriers to dissemination and provision of best practices have been identified, and include providers' underestimation of the problem in clients they serve, and confusion about how to best respond to information about clients' risk and infection status. To implement and sustain best practices interventions for this vulnerable group of clients, integrated procedures to change the knowledge, attitudes, training resources and practices of community mental health providers are required. Procedures for dealing with blood-borne pathogens should be structured to be a standard part of multidisciplinary team treatment. They should include a very basic set of evidence based practices for HIV, Hepatitis B and Hepatitis C, including screening, diagnosis, counseling, risk reduction, immunization, linkage with appropriate medical providers, and support for clients through treatment. We propose, in this Exploratory/ Developmental Grant application (R21), to develop an easily disseminated intervention, packaged as a "toolkit" and supported by implementation assistance, to enhance the knowledge, attitudes and practices of typical community mental health providers so that they will achieve sustainable, best practices standards for their infected and at-risk clients.